Activity 8-1: Once Upon an Oak Tree
Summary Students learn about species interactions by listening to and completing the story about the interactions between organisms around an oak tree.
✓ identify the species interactions that occur in the story.
✓ evaluate these interactions and categorize them.
- Writing materials
- Drawing materials (optional)
You may want to make an audiotape of yourself or someone else reading the story.
Estimated Time One 50-minute period
Language Arts Students write the conclusion to a story about an oak tree.
Visual/Performing Arts Students draw and/or perform their stories.
Prerequisites and Background Information
Introduce Activity 8-1 by reviewing pages 47-54 of the text and discussing the concept of competition. Encourage students to listen for the concepts described in the text as they hear the story being read to them.
Steps 1-2 Remind students about good listening skills. Use voice intonations to make the story come alive. Read the story to your class or play an audiotape with the prerecorded story.
Extend Activity 8-1 by having students create a story using a food web as a template.
Have interested students develop a role-playing exercise, a dramatic presentation, or a puppet theater to present their stories.
Step 3 After reading the story or playing the audiotape, provide each student or group of students with a copy of the story (Activity 8-1 Resource) and have them work together on Step 2 of the Procedure. Encourage students to offer comments, raise questions, and discuss questions with each other.
Ask students to complete or expand the Story, adding events that might continue to happen during the course of a day. If students need ideas for how to continue the story, direct them to the questions in Step 3 of the Procedure in the Student Edition. You may want to have them present their completed and expanded stories in one of the following ways:
- Small booklets
- Poster displays
- Bulletin boards
- Oral presentations
- Videotaped presentations
Conclude Activity 8-1 by reconvening the whole class and asking the students to consider what would happen if certain events occurred to disrupt some of the species interactions described in the story. Some possible disruptive events include the following:
- One species is affected severely by disease or drought.
- A forest fire sweeps across the area.
- A species is reduced considerably in number because of a particularly hard winter.
You may want to have students complete the story in writing or through drawings. Alternatively, you may want to have students take turns adding to the story orally as you go around the room from student to student.
Students can work individually or in small groups on this activity. If you elect to have students work in groups, you may want to assign a specific organism to each student in the group as the group continues the story.
Use the completed and expanded versions of the Story to assess if students can
✓ describe the interaction between different species in the same habitat.
✓ compare and contrast different types of interactions that occur, such as competition, predator-prey, parasitism, and mutualism.
A suggested response will be provided upon request. Please send an email to firstname.lastname@example.org.
Another example of mimicry is the flower fly, which is shown in Figure 8.7. It is actually a fly and a lot like the ones that buzz around garbage on a hot summer day. But it is black with bright yellow stripes. What do you think the flower fly is mimicking and why? What might be the advantage of this mimicry for the flower fly?
- Sample answers to these questions will be provided upon request. Please send an email to email@example.com to request sample answers.
- What do ecologists mean by the word competition?
- What is the difference between a predator and a parasite?
- Describe an example of mutualism with which you are familiar, and that isn't explained in this book.
Activity 8-1 Resource: Once Upon an Oak Tree (Student Reproducible)
Imagine yourself walking along a trail in an oak forest. The wind blows lightly through the trees, and the birds peep and squawk as you pass. The forest floor is slightly damp from the lack of sunlight. You notice the sweet, pungent smell of moist leaves and earth under your feet. It is darker here in the woods than out in the meadow. There isn't a glare from the sun. Here, everything seems clear and distinct. You become aware of individual animals and plants as they encounter each other. One particular oak captures your attention and you decide to sit down by it. You sit cross-legged in front of it and look up as if you're going to have a conversation with it. Instead you sit quietly, watch, and listen.
A fox family has hollowed out the ground around the roots of the tree. This is the fox family's area where they bring meals of mice and squirrels. Your eyes move up the trunk slowly, as you watch a trail of ants marching in line around the tree. The ants seem to spend their whole lives looking for seeds and other bits of food. They have another job, too, one that helps out another organism. The ants carry pale green insects slightly larger than themselves to tasty, tender new plant shoots. While these pale green aphids are eating, a sweet liquid comes out of their bodies. The ants then feed on this sweet liquid. As you look closer, the ants seem to be taking care of the aphids, protecting them from animals that would eat them.
Again your eyes wander over the curves and slopes of the oak tree until you see another insect. It's a bark-boring beetle with a long tube at its head. You wonder what it's up to until you notice that the long tube is drilling into the bark. The beetle is using the long tube to remove the bark. You wonder if it is boring in to eat the layers of the tree underneath.
Or, maybe the beetle is a female boring a place to lay her eggs in the bark so her larvae will have food to eat when they hatch. Or, maybe it's accomplishing both tasks. Bark-boring beetles bore tunnels throughout the bark, eating as they go. Suddenly, the quiet is disturbed by the sound of tapping above you. You glance upward to where the noise is coming from and see a woodpecker higher up on the trunk. Its head moves quickly back and forth. The woodpecker is tapping at the bark to get to the plump, juicy larvae underneath. The woodpecker is probably feasting on the larvae of another bark-boring beetle. Another creature that loves the beetle larvae is a particular kind of fly. It lays its eggs by drilling right through the bark, into the larvae's bodies! The eggs then hatch to devour the flesh of the beetle larvae!
As you consider this tasty thought, a light shower of bits of leaves and bark falls into your hair. You brush off the debris and look up quickly. You see two squirrels scurry across the branch above you. The squirrels leap from branch to branch, finally racing down the trunk to the ground. Eventually, they lose interest in each other as they begin searching the ground for acorns. Several blue jays swoop down from the sky through the branches to join the squirrels in the search for acorns.
The jays squawk and flutter their wings trying to chase the squirrels away. But the squirrels go on searching. While the squirrels and jays forage for food, you notice a black speck on top of an oak seedling drop onto a jay as the bird passes under it. The jay doesn't notice the black speck and keeps looking for food. You realize that the black speck is a tick. The female tick has found a new home on the jay. It may have waited on that seedling for a long time, even years, for a warm-blooded animal to pass under it. When the tick lands on something warm, it burrows into the animal's skin. There the tick feeds on the animal's blood until it's full. When the tick is gorged with blood, it lets go of the animal, lays its eggs, and dies. Through all of that the jay may only feel a sore spot on its back for a short time.
Suddenly, you realize you're a warm-blooded animal and another tick could find you delicious. So you decide it's time to go. Standing, and backing up a few steps gives you a new view of the oak. You realize that something you thought was part of a branch is actually an owl. Its dark feathers keep it hidden from most creatures until night falls. Then it leaves its nest, which is actually an abandoned craw's nest, to hunt for food. Owls are effective hunters but lazy builders. So they often use other animals' nests. The owl spends much of the night hunting for mice, rabbits, and moles.
As you walk away from the oak, you turn around once more to look at the whole tree. The branches up against the sky show several dense jumbles of twigs, which you can see now are bunches of mistletoe. The mistletoe clings to the tree and drains the nutrients from its branches. If there are enough mistletoe plants on the tree, eventually it will die.
You think about how much was going on during your short visit with the oak tree. And as you walk back down the trail, you wonder if every oak tree is as busy as the one you just visited.